The present invention relates to a filter having a filter housing, having a housing cover that seals the filter housing during operation and can be removed from the filter housing, having an inlet for liquid that is to be filtered and having an outlet for filtered liquid, having an exchangeable filter cartridge that separates a raw side and a clean side of the filter from one another, made up of a valve seat and a valve body that is movable relative to the seat and having a valve body preloaded with a force acting in the valve closing direction, the valve seat being situated in or on the housing cover, fixed to the cover, the valve body being guided in or on the housing cover, fixed to the cover, and a spring that preloads the valve body and the valve closing direction being guided in or on the housing cover, fixed to the cover.
In addition, the present invention relates to a filter cartridge for the filter.
A filter of the type named above is known from DE 10 2012 210 900 A1. In the housing cover of the filter, a filter bypass valve is fixedly installed, the parts of the filter bypass valve being situated in a valve housing that is fixedly connected to the cover. The spring of the filter bypass valve is, on the one hand, supported on the valve body of the filter bypass valve and, on the other hand, on the valve housing, so that the spring is always pre-tensioned, and the valve body is always loaded with a pre-loading force acting in the valve closing direction. A change in the pre-loading force of the valve body, in order to change the desired opening pressure of the filter bypass valve, is possible here only through the use of a different spring or through the use of a different valve housing having a modified supporting of the valve spring. Both of these are relatively costly, and require significant constructive interventions in the housing cover, which can be carried out only during the filter production.
DE 20 2014 104 029 U1 discloses a filter that is used as a replacement for a screw-on exchangeable filter that can be replaced only as a whole. The filter has a base plate that, after being screwed onto a connecting flange for the first time, for example of an internal combustion engine, remains there permanently. A filter bypass valve is situated entirely on the base plate. A spring of the filter bypass valve is supported by an exchangeable filter cartridge of the filter and is pre-tensioned when the filter cartridge is installed in the filter.
DE 10 2009 054 523 A1 discloses a filter in which the valve body and the valve spring of the filter bypass valve are parts of a filter housing cover. The valve seat of the filter bypass valve is provided on a cover-side end plate of the filter cartridge. The spring of the filter bypass valve is supported, on the one hand, on the inside on the filter housing cover, and, on the other hand, on the upper side, facing the filter housing cover, of the valve body. The spring of the filter bypass valve here is already pre-tensioned even when no filter cartridge is yet situated in the filter, and acts from above, i.e., from the cover side, on the valve body, pressing it downward, that is away from the filter housing cover, against the valve seat, i.e., in the direction from the filter housing cover toward the filter cartridge.